Magnetic record



y 1951 DE wr rT R. GODDARD 2,550,803

MAGNETIC RECORIT Original Filed June 18,1947

INVENTOR DEWIT'I R. E UDDHRD BY ATTO R-N EY Patented May 1, 1951 MAGNETIC RECORD De Witt R. Goddard, Riverhead, N. Y., assignor to Radio Corporation ofAmerica, a corporation of Delaware Original application June 18, 1947, Serial No. 755,331. Divided and this application August 24, 1949, Serial No. 112,049

2 Claims.

' The subject matter of this invention is a divi- Records.

This invention relates to magnetic sound recording and reproducing apparatus and has special reference to the provision of improvements in telegraphones of the type employing socalled paper tape records, and to improvements in such records, per se.

Telegraphone records made of paper tape coated with comminuted paramagnetic particles have, by reason of their low cost and ease of handling, largely supplanted records made of solid metal. However, a paper tape record cannot accommodate a recording of a length as great as can be applied to a solid metal tape of the same dimensions. This is so because the former must be magnetized in a longitudinal direcinvention is to provide an improved paper tape telegraphone record and one capable of accommodating a longer recording than has heretofore been thought possible of practical achievement with paper tape records.

Another object of the present invention is to provide an improved method of, and apparatus for, making a relatively long-playing recording on a magnetizable tape record of, a relatively short overall length.

Another and important object of the present invention is to provide an improved telegraphone of the type employing a tape-like record, and one suitable 'for the automatic repetition of advertisements, announcements, notices, explanations, warnings or the like in stores, elevators, vending machines, threatres, trafiic intersections, etc.

Another and specific object of the present invention is to provide a tape record which may be played back immediately, i. e. without rewinding the "tape.

Still another object of the present invention is to provide an improved two-sided telegraphone record and one wherein the possibility of crosstalk between the magnetic signals on the opposite sides of the record is minimized.

The invention will be described, in connection with the accompanying drawing wherein: Fig. 1

is a view in perspective of a paper tape-record constructed in accordance with the principle of the invention; Figs. 2 and 3 are similar views in perspective of the tape of Fig. 1 but with the tape marked. to show the direction of the magnetic lines of force on its opposite major faces; Fig. 4 is a cross-sectional view of a modified tape construction Within the invention and Fig. 5 is a partly diagrammatic view in perspective of a telegraphone including a sound-head and reeling system for a tape record, all constructed and arranged in accordance with the principle of the present invention.

The present invention contemplates and its practice provides a telegraphone-record comprising a paper or other non-metallic flexible tape or ribbon R which may be in the form of a closed loop L, having a half-twist T therein and provided on both of its major faces A and Bwith a sound track constituted of adherent comminuted paramagnetic particles m, m. When, as shown in the drawings, the tape is provided with a half-twist and its major faces are joined, front to back, as at S by pasting its ends together, the magnetic major surfaces A and B form a continuous sound-track twice as long as the sound track on a conventional single-sided tape record of the same length. Furthermore, it is apparent that this endless telegraphonerecord need not be re-reeled before playing it back and is thus especially suited for the automatic repetition of announcements etc.

In recording (or playing-back) conventional single-sided tape records, the magnetic polepieces in the soundhead are disposed at a right angle to the line of movement of the tape. Such an arrangement might give rise to cross-talk in recording or playing back of the two-sided records of the present invention. Accordingly, referrin now to Fig. 5, in carrying the present invention into effect the pole pieces P and P of the sound head H are arranged at an angle of from say 20 to say 45 with respect to the axis of movement of the tape R. It will be observed that where, as in the instant case, the sound head is disposed at an angle of 45 with respect to the line of movement of the tape then the magnetic lines of force (see Fig. 2) and (see Fig. 3) on the opposite faces A and B of th tape are at an angle of with respect to each other. At this optimum angle the possibility of interference between the recordings on the opposite sides of the tape is minimized.

In the alternate form of telegraphone record shown in cross-section in Fig. 4 th paper or other non-metallic flexible base R is provided with one or more layers 2', z" of soft iron particles of other material having low magnetic retentivity. Such a layer or layers may be said to comprise a magnetic shield between the outer magnetically sensitive layers m and m and, in any event, retains a minimum amount of the magnetic flux to which the tape is exposed during the recording interval. The intermediate layer or layers i, z" serve not onl to isolate the magnetically active coatings m and m but also to improve the performance of the record since the soft iron reduces the reluctance of the air-gap G between the pole pieces P and P of the record- 9 ing or play-back head H.

, that although the splice S in the tape R, forms a right angle with respect to the edge of the tape, the angular disposition of the sound-head H causes the splice to approach the air gap G at e an angle and thus prevents any disturbing noise such as might occur if th splice were to be brought abruptly into register with the said gap.

What is claimed is:

1. A telegraphone record comprising a twosided non-magnetic base provided on each of the two sides with a magnetizable sound track, and means for magnetically isolating said sound tracks each from the other, said means comprising metallic material of low magnetic retentivity supported on said base intermediate said magnetizable sound tracks.

2. A telegraphone record comprising a nonmetallic tape in the. form of a closed loop and provided on each of its major faces with a layer of magnetizable material, and wherein said tape is provided with a layer of metallic material of low magnetic retentivity intermediate said layers of magnetizable material.

DE VVITT R. GODDARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,442,682 De Forest Jan. 16, 1923 1,882,336 Nakken Oct. 11, 1932 2,229,293 Huntley et a1 Jan. 21, 1941 2,479,868 Rossmann et a1. Aug. 23, 1949 2,496,047 Goddard Jan. 31, 1950 FOREIGN PATENTS Number Country Date 512,766 Great Britain Nov. 20, 1937 

